THE THE ““NEWNEW”” DISEASE IN DISEASE IN TEXAS AFTER FOUR TEXAS AFTER FOUR YEARS: WHEREYEARS: WHERE’’S IT S IT
GOING?GOING?THOMAS ISAKEITTHOMAS ISAKEIT
PROFESSOR AND EXTENSION PLANT PROFESSOR AND EXTENSION PLANT PATHOLOGIST PATHOLOGIST
TEXAS A&M UNIVERSITY TEXAS A&M UNIVERSITY COLLEGE STATIONCOLLEGE STATION
TWO INVASIVE DISEASES: THE OLD AND THE “NEW”
SORGHUM ERGOT: NOT GENERALLY A PROBLEM, BUT IT PREVENTS A FALL SEED PRODUCTION IN SOUTH TEXAS
HEALTHY DISEASED: PROFUSE SECONDARY CONIDIA
IN A FEW YEARS, WE KNEW THE YIELD LOSS POTENTIAL OF SORGHUM ERGOT AND ITS OVERWINTERING PATTERN
WHAT HAVE WE LEARNED ABOUT SOYBEAN RUST SO FAR?
2006 (DRY) – AUGUST DETECTION
SPRAY ADVISORY FOR LIBERTY COUNTY
2% OF 155,000 ACRES
2007 (WET!) – JUNE DETECTION
WIDE-SPREAD SPRAY ADVISORY
88% OF 92,000 ACRES
NEVER FOUND!
2008 (DRY) – JULY DETECTION
SPRAY ADVISORY FOR LRGV
0.1% OF 205,000 ACRES (SEED PRODUCTION) DOLLY!
BROWNSVILLE, TEXAS – 11/15/08
DETECTED 10/13/08 @ R3-4; SPRAYED LATER
SPRAYED NOT SPRAYED
BROWNSVILLE, TEXAS – 11/15/08
DETECTED 10/13/08 @ R3-4; SPRAYED LATER
HARLINGEN, TEXAS – 12/3/08
R5, NEVER SPRAYED
HARLINGEN, TEXAS – 12/3/08
R5, NEVER SPRAYED
2009 (DRY) – NOVEMBER DETECTION
SPRAY ADVISORY FOR LRGV
0.1% OF 195,000 ACRES (SEED PRODUCTION)
PUCCINIA PATHWAY APPLICABLE FOR PHAKOPSORA ONLY IN 2007
WHY THE PUCCINIA PATHWAY WON’T ALWAYS WORK FOR SOYBEAN RUST
IN SOUTH TEXAS :•
- LACK OF A CONSISTENT OVER-WINTERING SOURCE
- NEED FOR RE-INTRODUCTION EARLY IN SEASON
OVER-WINTERING OF KUDZU
FREEZE PROBABILITY (BASED ON 27 YEARS DATA)
AREA OF KUDZU IN EAST TEXAS: EST. 400 A IN FORESTS
DAL
HOU
LUB
ELP
SAT
AUS
50%
100%
OVER-WINTERING: POLK COUNTY, 2/23/08(PROTECTION AND INFECTION (??) FROM LITTER)
(COMPLETELY UNDETECTABLE FOR SEVERAL MONTHS IN 2009)
OTHER HOSTS – CORAL BEAN (ERYTHRINA HERBACEA)
SURROUNDED FOR SEVERAL MONTHS ON 3 SIDES BY SOYBEANS WITH RUST!
BREWSTER COUNTY BLUEBONNETS, 3/11/08
(STILL NOT DETECTED ON THIS POTENTIAL HOST)
NOT WIDESPREAD: ESCAPES?
WIDESPREAD: APPARENTLY NOT A GOOD HOST
OTHER CROP HOSTS?
MOVEMENT FROM ELSEWHERE
NO RUST IN SOUTH TEXAS UNTIL NOV. 2009
TRENDS THAT CAN AFFECT THE INOCULUM SOURCE:
• - INCREASE IN PRODUCTION OF SOYBEANS IN THE LOWER RIO GRANDE VALLEY OF TEXAS AND ADJACENT RIO BRAVO AREA OF TAMAULIPAS, MEXICO
- TWO CROPS PER YEAR IN BOTH AREAS
MONITORING IN MEXICO – RIO BRAVO AREA, SEPTEMBER, 2009
• 2005: TOO LATE TO HAVE AN IMPACT!
• 2006: TOO DRY TO HAVE AN IMPACT!
• 2007: WIDESPREAD, BUT SMALL IMPACT
• 2008: TOO DRY, EXCEPT IN THE VALLEY, DURING A WET FALL
• 2009: CAN’T PREDICT WHAT WILL HAPPEN
CARRY-OVER IN HIDALGO COUNTY, 1/17/08
HIDALGO COUNTY VOLUNTEER SOYBEANS, 2/23/08
VOLUNTEERS: BROWNSVILLE, 2/26/09
•
TEXAS PROGNOSIS:SPRING CROP
FALL OR LATE-MATURING CROP
• MORE LIKELY TO GET A BREAK WITH DRY WEATHER
• CAN TAKE ADVANTAGE OF ADVISORIES
• WEATHER MORE FAVORABLE FOR RUST
• MAKE PLANS TO SPRAY
• NEED TO DESTROY CROP & VOLUNTEERS!
THE MOST COMMON LAND USE IN TEXAS IS ALSO RUST-AVERSIVE